Centralized traffic controlling system for railroads



yOct'. 27, 1936. w. T. POWELL CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed May 19, 1954 6 Sheets-Sheet l l WEA oLtLoU 2.3 :SES

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Oct. 27, 1936. w. T. POWELL CENTRALIZED TRAFFIC CONTROLLING sYsT'EMIFoR RAILROADS' k Filed May 19,*1'934 `vs sheets- Sheet 2 INKT/ENTOR w. :f -BY 7M M ATTORNY Oct. 27, .1936. POWELL 2,058,824

CENTRALIZED TRAFFICl CONTROLLING SYSTEM FOR RAILBOADS 6 'Sheets-Sheet 5 Filed May 19, 1934 lNvENTo @WM-EM Filed May 19, 1954 6 Sheets-Sheet 4 Alu" alu ATTORNY w. T. POWELL F-led May 19, 1934 6 Sheets-Sheet 5 INVENToR ZU. 7.' W

BY MM w ATTORNY ocr. 27, 1936.

CENTRALIZED TRAFFIC CONTROLLING SYSTEM FCR RAILROADS SMV Oct. 27, 1936. w. T. PQWELL CENTRALIZED TRAFFIC CONTROLLING SYSTEM FOR RAILROADS Filed May 19, 1934 6 sheetssheet 6 m25 okmom www Patented Oct. 27, 1936 CENTRALIZED TRAFFIC CONTROLLING l SYSTEM FOR RAILROADS Winfred T. Powell, Rochester, N. Y., assignor to General Railway Signal Company, Rochester,

Application May 19,1934, Serial No. 726,525

24 claims'.

This invention relates to centralized traic controlling systems for railroads and it more particularly pertains to the communication part of such systems.

By means of the centralized traic controlling system `contemplated by the present invention, switches and signals at field stations along a railroad system are under the supervision and control of an operator at a central control oilice so that they can be positioned in accordance with the required traflic over the stretch of track equipped with the system. Likewise, the conditions oi the various traiiic controlling devices, such as the switch positions, the clear and stop signal indications and the like, are transmitted to the control oflice to provide the operator with such information as may be necessary for the proper governing of train movements.

The present invention more particularly relates to a centralized traffic controlling system wherein the supervision of the traiiic governing devices and the indication of their conditions are accomplished over a communication system having only two line Wires. These two line wires serve to co-nnect the control o-iiice with certain of the ield stations. The present invention is more particularly directed to a tralic controlling system in which the distance between certain of the eld stations and the control oice is such that it is impractical to transmit impulses from the control oiiice to certain distant eld stations because of the length of the line circuit.

The present invention contemplates the use of one or more repeater stations for repeating the impulses both ways over the communication system. In addition to the repeater station or stations, regular stations are connected to the communication system either between the control oiice and thev iirst repeater station or beyond the repeater station.

The apparatus at the control Voffice and at each field station is organized to be responsive to diiferent series of impulses arranged in distinctive combinations in accordance with the character of the messages desired to be transmitted for selecting stations for out-bound messages, for registering stations for in-bound messages and for the transmission of the required conditions after the station has been selected or registered. Each series of impulses causes the apparatus at the control oice and at all iield stations to operate through a cycle of operations.

More specically, a line battery or other suitable source of current is located in the control oiiice and a similar source of current is located at each eld station. The control oce operator may cause the transmission of a series oi posi tive and negative impulses in various combinations from the source located in the control oice to operate the system through a control cycle of operations. During a control cycle the regular eld stations between the control oice and the first repeater station (including the repeater station) are responsive to primary impulses supplied from the control oflice battery and the regular field stations beyond the repeater station are responsive to secondary impulses supplied from the repeater station battery.

Likewise any eld station may cause the transmission of a series of positive and negative impulses in various combinations from the source of current located at the station which is transmitting. If this is the repeater station nearest the control oflice or a regular station between this repeater station and the control olice the impulses are supplied from the station which is transmitting. If the transmitting station is beyond the repeater station then the impulses between the transmitting station and the repeater station are supplied from the source of current at the transmitting station, these impulses being recorded at the repeater station and repeated to the control oice from the source of current at the repeater station.

In other Words, during a cycle for the transmission of controls the control oiiice impulses the line circuit which extends to the rst repeater station with the control ofce battery and the repeater station repeats these impulses over the line circuit extending beyond the repeater station with its battery. For an indication cycle initiated at a station beyond the repeater station, the transmitting station impulses the line extending to the repeater station from the transmitting station battery and the repeater station repeats these impulses to the control office from the repeater station battery.

The impulses transmitted from the control oice and from a eld station are of substantially equal duration and are separated by substantially equal time spaces. They are made distinctive during transmission in either direction byV reason of their polarity.

Step-by-step meanslocated at the control oflice and at each field station operate in response to the impulses irrespectiveof their character. During a control cycle one of two distinctive messages or controls may be transmitted on each step by reason of the distinctive character (polarity) of the corresponding impulse applied to the line circuit. During an indication cycle one of two distinctive messages or indications may be transmitted on each step by reason of the distinctive character (polarity) of the corresponding impulse applied to the line circuit. In other words, it is possible to transmit controls with a choice of two on each step of a control cycle and to transmit indications with a choice of two on each step of an indication cycle. Since the system is of the simplex type it operates through separate cycles for the transmission of controls and indications.

Other features of novelty embodied in the present invention reside in the manner in which a line circuit connects the control office with a plurality of stations up to and including a repeater station and separate line circuit connects the repeater station to a plurality of other stations. The arrangement whereby proper synchronism is obtained during out-bound and in-bound cycles of transmission, with these impulses repeated at the repeater station during these cycles also is an important feature of the invention.

A further feature of the present invention resides in the manner in which the field stations are prevented from transmitting indications to the control office from moie than one station at any one time.

Another feature of the present invention resides in the manner in which the stepping relay bank at the repeater station, which responds to impulses from the control oice or from a distant regular station, repeats these impulses to distant stations or to the control oflice respectively.

These characteristic features of the present invention thus briefly stated will be explained more in detail in the following description of one embodiment of the invention and various other features, functions, and advantages of a system embodying the invention will be in part pointed out and in part apparent as the description progresses.

In describing the invention in detail reference will be made to the accompanying drawings in which similar parts throughout the several views are designated by similar reference characters, generally made distinctive either by distinctive exponents representative of their location or by reason of preceding numerals representative of the order of their operation and in which:-

Fig. 1A illustrates in a diagrammatic manner the line circuit and the more directly associated apparatus in a system embodying the present invention;

Figs. 1B, 1C, 1D, and 1E are schematic circuits showing the connections of the batteries to the line circuits under various conditions, which will be explained in detail.

Figs. 2A and 2B illustrate the apparatus and circults of a typical control cnice arranged according to the present invention;

Figs. 3A and 3B illustrate the apparatus and circuits employed at a typical repeater station in accordance with the present invention;

Fig. 4 illustrates the apparatus and circuits employed at a typical regular eld station in accordance with the present invention.

These drawings illustrate a system having a plurality of eld stations and a control oflice. For convenience in the description it is assumed that there is one repeater station between the control officeand a regular station, although it will be understood that additional regular stations may be connected between the control ofiice and the repeater station illustrated in Fig. 1A

and that additional regular stations may be connected beyond the regular station illustrated. Similarly additional repeater stations may be provided as dictated by the requirements of practice.

With reference to Fig. 1A, the control office is connected to the repeater station by means of a two wire line circuit comprising a control line and a return line. The repeater station is connected to the regular station by means of a two wire line circuit comprising a control line1 and a return linel. The back contact of the lockout relay at the end eld station is connected to the return line1 conductor at this station for` providing a closed circuit for the line extending from the repeater station to the end station. Similarly, back contact ISU of relay CKz at the repeater station is connected to the return line for providing a closed circuit for the line between the control oice and the repeater station. In this connection it will be understood that, when regular stations are connected between the control oflice and the repeater station, no back contacts similar to |50 of relay CK2 are provided for connecting the control line to the return line normally because such relays are not used at the regular stations. Therefore, the regular stations are connected in series in the line circuit (as indicated by contact 250 of relay L02), instead of terminating the line circuit as at a repeater station.

Although the embodiment of the present invention illustrates the repeater station and the regular station as having only a single switch and associated signals, it will be understood that the invention is not so limited since any desired number of switches and signals may be arranged to suit the track layout.

For the purpose of simplifying the illustrations and description, various parts and circuits have been shown diagrammatically and certain conventional illustrations have been employed, the drawings have been made more with the purpose in mind to make it easier to understand the principles and mode of operation of such a systern rather than with the idea of illustrating the particular construction and arrangement of parts that would be employed in actual practice. Thus the relays and their contacts are illustrated in a conventional manner and symbols are used to indicate connections to the terminals of batteries or other suitable source of electric current instead of showing all of the wiring connections to these terminals.

In some of the drawings, Figs. 2A, 2B, 3A, and 3B, for example, certain relays have been shown in full lines on one drawing and in dotted lines on an adjacent drawing. The relays shown in dotted lines have been given the same reference characters as applied to these relays shown in full lines since they are the same relays and they have been connected by dotted lines extending between the drawings. The relays shown in dotted lines have the circuits of their windings omitted, all of which is for the purpose of simplifying the drawings as much as possible.

The symbols and are employed to indicate the positive and negative terminals respectively of suitable batteries or other sources of direct current. The symbol (CN) is employed to indicate a center or intermediate tap of a battery or other source of direct current, of which the terminals of this source are indicated by the terminals (B+) or (B-).

Control olice equipment-The control oflice equipment includes a biased-to-neutral, polar line relay F which repeats the impulses applied to the line circuit by battery B in the control oiice or by battery B1 at the repeater station. Relay F actuates its polar contacts to the right when the control ofce applies impulses of (-1-) polarity to the control line with current from battery B and when the repeater station applies impulses to the control line conductor from battery B1. Neutral line repeating relay FP, of the quick acting type, repeats the impulses applied to relay F irrespective of their polarity. Slow acting relays SA and SAP are used to denne the bounds of an operating cycle. They are picked up in sequence at the beginning of a cycle and dropped in sequence at the end of a cycle. Due to their slow acting characteristics they remain picked up during the intermittent operation of relay FP.

A cycle determining relay S of the neutral type is normally deenergized to provide a closed line circuit at the control olice and to connect the control cnice battery to the line circuit when it is energized during a control cycle. The particular polarity applied to the line circuit at the control oiiice for the transmission of controls is determined by code selecting relay CS. Cycle checking relay CK remains down during the transmission of controls and is picked up during a cycle for the transmission of indications. Impulse relays E and EP time the length of the impulses and the spaces between impulses, these relays operating in response to the stepping operation of the system.

A suitable step-by-step relay bank is employed including relays VP, lV, 2V, 3V, and LV. Relays lV, 2V, 3V, and LV take their steps during the deenergized or oli periods of the line circuit and relay VP shifts its position during the energized or on periods of the line circuit. When the stepping relays are picked up they are stuck up until the end of the cycle. Half-step relay VP is picked up and dropped during alternate on periods of the cycle.

The control oice also includes a starting relay STR which is molL entarily energized at the start of a control cycle and which remains down during an indication cycle. The oiiice is provided with a suitable control machine which includes a miniature track diagram ts representative of the actual track layout in the field, together with control levers and buttons which are manually operable to obtain the desired control. As typical of such levers, switch machine control lever SML and starting button SB have been indicated in Fig. 2A.

A similar starting button is provided for each group of control levers and is associated with a particular eld station, so that the positioning of the control levers for a particular station results in the transmission of controls to that station following the operation of the associated starting button. Switch machine lever SML is typical of other levers which are ordinarily provided, such as signal control levers but these latter levers have been omitted since a description of the operation controlled by lever SML is typical of the control by the additional levers.

instead of showing the actual circuits and means associated with the several starting buttons for accomplishing the initiation of the system and for allowing the transmission of controls to Yonly one station at a time,A such control has been merely indicated by a dotted line connecting button SB with relays SR and CD. The

means which may be provided to obtain these results includes storing relay SR and code determining relay CD, one of each for each starting button. The relays SR and CD for a particular station are so interlocked with the other SR and CD relays for other stations that only one CD relay can be energized at any one time irrespective of the number of SR relays which are picked up. Such an arrangement of SR and CD relays has been completely shown in prior applications such, for` example, as in the pending application of N. D. Preston et al. Ser. No. 455,394 iiled May 24, 1930, corresponding to Australian Patent 1501 of 1931. It is believed, however, that the K above discussion of the SR and CD relay operations is sufficient for an understanding ci the operation oi the present invention.

As .typical of the station registering means in the control oiilce, pilot relays lPT and EPT selectively actuated on the first two steps of the cycle have been illustrated. For illustrating station selection by a particular combination of positions of the tWo pilot relays, a station relay ST has been illustrated. It will be understood that additional pilot relays can be provided for additional steps for individually registering a larger number of stations when required.

For the purpose of illustrating the storing of indications from a registered station, indicating storing relay IR has been illustrated as being operated on the third step of the cycle. This relay is provided with a circuit for operating the track occupancy lamp GS. It will be understood that additional indication storing relays may be provided for operating additional devices of which lamp OS is typical.

Repeater station equipment-With reference to Figs. 3A and 3B, the repeater station includes a track switch TSl which is operated by a switch machine SM1 of any suitable type. The position of the track switch is repeated by the usual switch repeating relay which is not shown in the present embodiment. The occupied and unoccupied condition of the track section is indicated by track relay T1 being energized to indicate the unoccupied condition of the track and deenergized to indicate the occupied condition of the track with which it is associated.

The traffic over the track switch is governed in accordance with the signals illustrated but the control of these signals is not shown since this control may be accomplished in a similar manner to the control of the switch machine by means of polar impulses received after the station is selected.

The selection of the illustrated station for contro-ls is accomplished by pilot relays iPT1 and ZPT1 which are selectively positioned on the firstV two steps of the control cycle in accordance with the polarity of the impulses transmitted from the control oliice. Change relay CHl is for the purpose of initiating the system into a cycle of operations from this station when a change takes place which requires the transmission of new indications. The circuits for controlling this relay have been omitted, since it is well understood how such a relay is deenergized by the shifting of contacts on the track relay or the switch repeating relay.

The communication part of the system includes a biased-to-neutral, polar relay F1 and its repeating relays FP1, SA1 and SAP1 operating in synchronisrn with and in a similar manner as corresponding relays in the control oflice.

Two checking relays 0K1 and CK2 are provided, the first being picked up throughout a control cycle and the second being picked up throughout an indication cycle. Code selecting relay CS1 selects the polarity of the impulses applied to the line circuit leading to the more distant stations during a control cycle and also for selecting the polarity of the impulses applied to the line circuit leading to the control oce during an indication cycle.

Lockout relay LO1 is provided for the purpose of selecting the circuits for positioning code selecting relay CS1 in accordance with the location from which impulses are transmitted. In other words, when the repeater station is transmitting to the control oiiice, relay L01 is picked up so that relay CS1 is positioned in accordance with the code jumper connections and the indications to be transmitted. If relay L01 is down relay CS1 is positioned in accordance with the positions ci line relay F2 which responds to the impulses transmitted from a station farther out the line.

The repeater station is provided with a bank of stepping relays IV1, TV1, 3V1, LV1 and associated half step relay VP1. The stepping relay bank takes one step for each off period and the half step relay is shifted during each on period in synchronism with corresponding relays in the control office.

Regular field station equipment-With reference to Fig. 4, the regular eld station includes a biased-to-neutral, polar line relay F3 and its repeating relays FP2, SA2 and SAP2 operating in a similar manner to corresponding relays in the control ofce. This station includes a bank of stepping relays lV2, 2v2, 3W and the associated half step relay VP2 operating in synchronism with corresponding relays in the control oflice. It is to be understood that synchronism referred to does not mean that the relays at the regular station are energized and deenergized at exactly the same time as corresponding relays at the repeater station or at the control oice, since there may be other relay operations intervening to delay the operations at this station. This is because the impulses are repeated at the repeater station but synohronism is approximately attained.

Checking relay 0K3 is picked up throughout a control cycle and lockout relay L02 is picked up throughout an indication cycle initiated at this station. Code selecting relay CS2 selects the polarity of the impulses applied to the line1 at this station in accordance with the code combination to be transmitted. Change relay CH2 is for the purpose of initiating the system in response to a change in condition at this station which requires the transmission of indications.

For the purpose of selecting this station for the transmission of controls thereto, pilot relays IPT2 and 2PT2 are illustrated as being selectively positioned on the first two steps of the cycle. For the purpose of illustrating the transmission of controls to a selected station, switch machine control relay SMR2 is illustrated as being selectively operated on the third step of the cycle when the pilot relays are in proper positions for selecting this station.

Track switch TS2 is illustrated as being controlled by switch machine SM2 and the occupied and unoccupied condition of the illustrated track section is repeated by `track relay T2 in the usual manner. The control of the signals at this station has not been shown in detail, since the control of the switch machine may be considered typical of the manner in which additional steps of the cycle function to control signals in response to additional impulses. Lockout relay LO3 at the end station is illustrated in the upper right hand corner of Fig. 4 for the purpose of showing that the line circuit is normally closed at the end station.

It is believed that the invention will be best understood by setting forth in the following description various typical operations in detail.

General operation 'I'he system of the present invention is normally in a condition of rest from which it may be initiated into a cycle of operations either from the control oflice or from any of the field stations whenever there are new controls or new indications respectively to be transmitted.

Although new controls and indications may occur simultaneously, the system is so arranged that only controls or indications may be transmitted during any one particular cycle. In case new controls and indications become ready for transmission simultaneously, the system is so arranged that the resulting cycle is for the transmission of indications. As long as there are indications awaiting transmission, the system functions to transmit these indications before permitting the transmission of controls from the control oince. In other words, indication conditions are superior to control conditions when both exist with the system in its normal condition.

While the system is in its normal condition the line circuit is deenergized. The energizaton of the line circuit with potential during the conditioning period at the start of a cycle renders the succeeding cycle effective for the transmission of controls. The energization of the line circuit with a potential during the conditioning period at the beginning of a cycle renders the succeeding cycle effective to transmit indications.

For convenience in describing the present invention a primary impulse applied to the control line circuit (see Fig. 1A) will be considered as an impulse which causes current to flow from left to right in the control line. Similarly, a secondary impulse applied to the control line1 circuit will be considered as causing current to flow from left to right in the control line1. During an indication cycle, a impulse applied to the line circuit from the regular station will be considered one which causes current to ow from right to left in the control line1. Similarly, a impulse applied to the line circuit from the repeater station during an indication cycle will be considered as causing current to flow from right to left in the control line.

Normal at rest condition-With the system in its normal condition, the line circuit extending from the control ofce to the repeater station and the line circuit extending from the repeater station to the regular station are both deenergized. With relay S in the control office deenergized, a return path is provided for current in the control line so that this line can be energized with or impulses from the repeater station When its relay CK2 is picked up. With relay CK2 deenergized, a return path is provided for current in the control line so that this line can be energized from the control oiiice when relay S is picked up. .'Siimilarly,V with relay L02 at the regular station deenergized, a return path is provided for current l figures.

, CS, to (CN).

in the control line1 so that this line can be energized with or impulses Afrom battery B1 as long as relay CK1 is energized. With relays CK1`= and LO1 deenergized, a return path is provided for current in the control line1 so that this linecan be impulsed with (-I) or impulses from the regular station When its relay L02 is picked up.

Schematic sketches Figs. 1B, 1C, 1D, and 1E show the various fundamental line circuit connections during various conditions of the communication system. For example, Fig. 1B indicates the connections of batteries B, B1, and B2 in the control oiice, the repeater station and the regular station respectively, to show that normally there is no ow of current in either line circuit. Fig. 1C indicates the connections of the .battery B1 at the repeater station flows through line relays F2 and F3.

It will be understood that the reference characters associated with the line relays in these schematic drawings refer to the line relays having the same reference characters in the other It will also be understood that the batteries shown are reversibly connected to the line circuits for providing and energization.

Fig. 1D indicates the conditions of the line circuits when indications are being transmitted from the repeater station to the control oflice. Under this condition line relays F and F1 are energized from battery B1 at the repeater station, with battery B in the control ofce connected to the line circuit by only one terminal so that the line is not energized from the control oiiice battery. Similarly, the vline circuit extending outward-from the repeater Vstation is not energized, since Vonly one terminal of each battery B1 and battery B2 is connected to this line. The interruption or break inthe battery circuit is provided under this condition at back contact |53 of relay L01 since this relay is picked up.

Fig. 1E indicates the condition of the line cir- ,cuits when indications are beingl transmitted from the regular station to the control oiiice. Under this condition the control oilice battery is not effective to energize the control line circuit since only one of its terminals is connected thereto. The repeater station battery B1 is effective to energize the control line circuit and the regular station battery B2 is effective to energize the control line1 circuit. It will be noted that, although the control line is connected to the return line1 with the terminal of each of the bat- ,teries B1 and B2 connected to the circuit, there is no interference or faulty operation caused by this connection of the two line batteries because the tie between the two line circuits consists of only a single conductor with no return path.

Relay CS in the control office (see Fig. 2A) is normally energized for positioning its polar contacts to the right over a circuit which extends from (B+) back contacts I4, I5 and I6 of relays IV, 2V, and 3V respectively and Winding of relay At the repeater station, track relay T1 is normally energized, since it is assumed that the associated track section is unoccupied. Change relay CH1 is normally energized, since it is assumed that no change has taken place at `this station since the last cycle of operation. At

track section is unoccupied. Relay CH2. is nor- Vrnally energized, since it is assumed that no `25,5 of relays IV2, 2V2, and 3V2 respectively, back contact 256 of relay CK3 and winding of relay CS2, to (CN).

vIVL'am/ual start- It will first be assumed that the operator in the control ofiice desires to move track switch TS1 at the repeater station from its normal locked position to its reverse locked p0- sition. It will be assumed that the repeater station responds to a code combination of and on the first two steps respectively of the communication system. It Will also be assumed that the trackl switch is operated to its reverse position in response to a impulse on the third step of the system.

With the system in its normal condition, the actuation of starting button SB in the control oiiice is effective to pick up relays SR and CD. The picking up of relay SR initiates the system into a cycle of operations and the picking up of relay CD determines the station selecting code ,and the controls to be transmitted over the line circuit. It will be understood that the storing relays such as relay SR can be picked up at any time the corresponding starting buttons are actuated, but only one code determining relay such as relay CD can be energized at one time and only while the system is in its normal condition.

The picking up of relay SR closes a circuit for picking up relay STR extending from front Contact il of relay SR, back contact I8 of relay SAP and winding of relay STR, to The picking up of relay STR closes a circuit for picking up relay S which extends from front contact I9 of relay STR, back contact 2li of relay CK and Winding of relay S, to The picking up of relay S closes a stick circuit for itself extending from back contact 2l of relay SAP, back contact 22 of relay CK, front Contact 23 and Winding of relay S, to Relay S remains stuck up during the control cycle because relay SA closes its front contact 24 before relay SAP opens its back contact ZI and because relay CK does not pick up its back contact 22 during such a cycle.

The picking up of relay S closes a circuit for energizing the control line circuit with a impulse which extends from the terminal of battery B, contact II! of relay CS in its right hand position, front contact I! of relay S, Winding of relay F, back contact I2 of relay EP, control line conductor, winding of relay F1, back contact IEEI of relay CK2, return line conductor i and contact I3 of relay CS in its right hand in its right hand dotted position and windingvv of relay FP, to Relay FP closes a circuit for picking up relay SA which extends from front contact 26 of relay FP and winding of relay SA, to Relay SA closes a circuit for front contact 21 of relay SA and Winding of relay SAP, to' Relay SAP closes a circuit for picking up relay VPY which extends from front contact 30 of relay SAP, front contact 3|- L picking up relay SAP which extends from of relay FP, back contacts 32, 33 and 34 of relays 3V, 2V and IV respectively and winding of relay VP, to Relay VP closes a temporary stick circuit for itself extending from front contact 3|] of relay SAP, front contact 36 of relay VP and over the remainder of the previously described pick up circuit to the winding of relay VP.

The picking up of relay VP closes a circuit for picking up relay E which extends from front contact 24 of relay SA, front contact 2| of relay SAP, front contact 31 of relay VP, back contact 38 of relay IV and winding of relay E, to The picking up of front contact 39 of relay E extends this circuit to the winding of relay EP for causing this latter relay to be picked up. The picking up of relay SAP deenergizes the circuit of relay STR at back contact I8 and this relay is dropped after a comparatively long interval of time. The picking up of relay EP deenergizes the control line circuit at back contact |2 which marks the beginning of the first off period.

Referring to the repeater station, the energization of relay F1 closes a circuit for picking up relay FP1 which extends from contact |62 of relay F1 in its right hand dotted position and Winding of relay FP1, to Relay FP1 closes a circuit for picking up relay SA1 which extends from front contact |63 of relay FP1 and winding of relay SA1, to Relay SA1 closes a circuit for picking up relay SAP1 which extends from front contact |64 of relay SA1 and Winding of relay SAP1, to

The energization of relay F1 closes a circuit for picking up relay CK1 which is effective before relay SA1 picks up its contacts and which extends from (B+), Contact |65 of relay F1 in its right hand dotted position, back contact |66 of relay SA1, back contact |61 of relay CK2 and upper winding of relay CKl to (B Relay K1 closes a stick circuit for itself extending from back contact |68 of relay SAP1, front contact |69 of relay CK1, back contact |16 of relay CK2 and lower winding of relay CK1, to Since relay SA1 applies to this stick circuit at its front contact |1| before relay SAP1 picks up its back contact |68, relay CKl is maintained energized over its stick circuit throughout this cycle.

The picking up of relays SA1 and CK1, with relay F1 positioned to the right, closes a circuit for positioning relay CS1 to the right extending from (B+), contact |65 of relay F1 in its right hand dotted position, front contact |66 of relay SA1, front contact |12 of relay CK1 and winding of relay CS1, to (CN). As will be later described, a circuit is closed at the end of the cycle for positioning relay CS1 to the right so that the above described circuit is for the purpose of checking or insuring that this relay will have its contacts in their right hand positions at the start of the cycle.

With the contacts of relay CS1 positioned to 'the right and with relay CK1 picked up, a circuit is closed for energizing control line1 with polarity extending from the terminal of battery B1, Contact |52 of relay CS1 in its right hand position, front contact I 54 of relay CK1, winding of relay F2, back contacts |11, |55, |56, |51, and |58 of relays LV1, 3V1, ZV1, |V1, and CK2 respectively, control line1, winding of relay F3, back Contact 250 of relay L02, back contact 350 of relay L03 (at the end station), return line1 and contact |I of relay CS1 in its right hand position to the terminal of battery B1. By

an analysis of the circuits under this condition it will be seen that the line and battery circuits are connected as shown in Fig. 1C. This energization of control line1 positions the contacts of relays F2 and Ff1 to the right.

Relay F3 closes a circuit for picking up relay FP2 which extends from contact 251 of relay F3 in its right hand dotted position and winding of relay FP2, to Relay FP2 closes an obvious circuit at its front contact 258 for energizing relay SA2 and relay SA2 closes an obvious energizing circuit for relay SAP2 at its front contact 259. Before relay SA2 picks up its contacts a circuit is closed for picking up relay CK3 which extends from (B+), contact 260 of relay F3 in its right hand dotted position, back contact 26| of relay SA2 and lower winding of relay 0K3, to (B Relay CK3 closes a stick circuit for itself extending from back contact 263 of relay SAP2, front contact 264 and upper winding of relay 0K3, to This stick circuit is effective throughout the cycle because relay SA2 connects to the circuit at its front contact 262 before relay SAP2 removes from the circuit at its back contact 263.

The pick up and stick circuits of the stepping and half step relays at the repeater station and at the regular station have been omitted because these circuits are exactly the same as for the corresponding relays in the control office. Therefore relays VP1 and VP2 at the repeater station and the regular station respectively are picked up during the conditioning on period. During the following description of the operation of the system it will only be mentioned that the stepping relays and the half step relays at the stations operate, since it is obvious that these relays will operate in synchronism with corresponding relays in the control oflice when their circuits are controlled by the line repeating relays in the manner shown in detail for the control ofce relays.

It will be noted that the control line is energized slightly in advance of the energization of the control line1 due to the fact that, after the energization of the control line, relays F1 and CK1 must be energized before the control line1 is energized so that the operation of the relays at the regular station and relay F2 at the repeater station controlled over control line1 are delayed a short interval of time after corresponding relays controlled over the control line are operated.

Impulszng and stepping operations- In the above description the operations were explained in detail up to the beginning of the first off period, at which time the control line was deenergized by the picking up of relay EP. The deenergization of the control line restores relays F and F1 to their neutral positions, following which relays FP and FP1 are deenergized. Relays SA, SAP, SA1, and SAP1 are not deenergized during the step-bystep operations because the intermittent operation of the FP relays is at such a rate that the slow acting relays do not have time to drop their contacts. This statement also applies to the slow acting relays at the illustrated regular station as well as all other stations.

The dropping of relay FP closes a circuit for picking up relay IV which extends from front contact 2Q of relay SAP, back contact 40 of relay FP, front contact 4| of relay VP, back contact 63 of relay 2V and winding of relay |V, to Relay IV closes a stick circuit for itself extending from front contact 29 of relay SAP, front Contact l5 and winding of relay IV, to

( A holding stick circuit is closed for relay VP which extends from front contact 3i) of relay SAP, back contact 3i of relay FP, front contact 35 and Winding of relay VP, to

At the repeater station relay I V1 is picked up and stuck up over a similar circuit. Likewise at the regular station relay IV2 is picked up and stuck up over a similar circuit. The picking up of relay IV deenergizes the circuits of relays E and EP at back contact 38. These relays drop after a comparatively long interval of time so that the control line is energized by the dropping of back contact I2 of relay EP. The picking up of relay IV1 at the repeater station deenergizes control line1 at back Contact I5'I which results in dropping relays F2 and F3 to their neutral positions.

rLihe dropping of relay EP in the control oilice marks the beginning of the first on period. The energization of the control line at back contact I2 oi relay EP causes relays F, FP, F1, and FP1 to be picked up. The picking up of relay FP drops relay VP because its temporary stick circuit is open at back contact lill of relay IV and its holding stick circuit is open at back contact 3| of relay FP. A circuit is now closed for picking up relay E which extends from front contact 24 of relay SA, front contact 2l of relay SAP, back c-ontact 3'! of relay VP, back Contact I8 of relay 2V, iront contact 38 of relay IV and Winding of relay E, to Relay E extends this circuit by way of its front contact 39 to the Winding of relay EP Which picks up its back contact I2.

Relay VP1 at the repeater station is dropped in synchronisrn with relay VP in the olice for energizing the control line1 over a circuit extending from the (-l-) terminal of battery B1, contact E52 of relay CS1i (assumed to be in its right hand position), front contact hill of relay K1, Winding of relay F2, back contacts Il?, I55, and i56 of relays LV1, 3V1, and ZV1 respectively, front contact I5? of relay IV1, back contact I5?) of relay CK2, back contact I6! of relay VP1, control line1 and over the remainder of the previously described line circuit to the terminal of battery B1, by Way of contact I5I of relay CS1 in its right hand position.

The picking up of back Contact I2 of relay EP (above described) 4deenergizes the control line oircuit which marks the beginning of the second off period. Relays F, FP, F1, and FP1 are dropped. Relay 2V is picked up over a circuit extending from front contact 2f) of relay SAP, back contact Il of relay FP, back contact 4I of relay VP, back contact fill of relay 3V, front contact l2 of relay IV and winding of relay 2V, to Relay 2V closes an obvious stick circuit for itself at its front contact 56.

Relay 2V 11 at the repeater station is picked up at the same time. The picking up of relay ZV1 deenergizes the control line1 circuit at back contact |58 which results in dropping relays F2 and F3 to their neutral positions. Relay FP2 is now deenergized for causing relay 2V2 to be picked up and Winding of relay VP, to Relay VP closes its temporary stick circuit by Way of its front contact 36 and over the previously described circuit to its winding. Relay VP1 at the repeater station is picked up and stuck up at the same time. i

The picking up of relay VP1 energizes the control linel circuit by Way or front contact I 6I of relay VP1, back contact IIS@ of relay CK2, front contact 55 of relay ZV1, back contact IE5 of relay 3V1l, back contact II'l of relay LV1, Winding of relay F2, front contact lil@ of relay 0K1 and contact E52 of relay CS1 (assumed to be in its right hand position) to the terminal of battery B1. The terminal of battery B1 is connected to the return linell conductor at right hand contact I5! of relay CS1. Relays F2 and F3 are energized over this circuit so that relay FP2 picks up at the regular station for picking up relay VP2.

The picking up of relay VP at the control ofce energizes relay E over a circuit extending from (-I-), front contacts 2d and 2| of relays SA and SAP respectively, front contact 3l of relay VP, back contact (I9 of relay 3V, front contacts i8 and 38 of relays 2V and IV respectively and winding of relay E to front contact 39 of relay E extends this circuit to the Winding of relay EP which picks up its back Contact I2 to deenergize the control line` circuit.

The picking up of back contact I2 of relay EP marks Vthe beginning of the third 01T period. Relays F, FP, F1 and FPl are dropped. A circuit is closed for picking up relay 3V which extends from front contact 29 of relay SAP, back contact 4@ of relay FP, front contact @I of relay VP, front contact 3 of relay 2V and Winding of relay 3V to Relay 3V closes an obvious stick circuit for itself at its iront contact 6l. Before relay 3V picks up to deenergize the temporary stick circuit of relay VP, a holding stick circuit for this relay is provided from (-1-) front contact 30 o` relay SAP, back contact 3l of relay FP, front contact 35 and winding of relay VP to Relay 3V1 at the repeater station picks up in synchronism with relay 3V in the office.

The picking up of relay 3V1 deenergizes the control line1 circuit Vat back contact I55 which drops relays F2 and F3. The dropping of relay F3 causes relay 3V2 at the regular station to be picked up. The picking up of relay 3V in the control oice deenergizes the circuits of relays E and EP at back contact Q9 so that these relays drop.

The dropping oi back contact I2 of relay EP energizes the control line to mark the beginning of the third on period. Relays F, FP, F1, and FP1 are again picked up. Relay VP is now deenergized because its temporary stick circuit is open at back contact 32 or relay 3V and because its holding stick circuit is open at back contact 3l of relay FP.

Relay VP1 at the repeater station is sirnilarly dropped. A circuit is now closed for picking up relays E and EP extending from front contacts 24 vand ZI of relays SA and SAP respectively, back Contact El of relay VP, front contacts 39, 4B and 38 of relays 3V, 2V and IV respectively and Winding of relay E, to and through front Contact 39 of relay E and the Winding of relay EP, to

The dropping of relay VP1 at the repeater station energizes the control line1 circuit by Way of the previously described circuit through the wind- The picking up of? ing of relay F2 Which now extends through front contact I of relay 3V1, back Contact I59 of relay CK2 and back contact ISI of relay VP1. This picks-up relays F2 and F3 which results in relay FP2 at the regular station picking up to drop relay VP2.

The picking up of back contact I2 of relay EP in the control office deenergizes the control line circuit to mark the beginning of the change to normal oli period. This drops relays F, FP, F1, and FP1. The picking up of relays E and EP in response to the dropping of relay VP maintains the control line circuit open for a comparatively long interval of time as Will be later described. The comparatively long deenergization of the control linc circuit causes relays SA, SAP, SA-, and SAP1 to release. The dropping of relay SA deenergizes relays E and EP at iront contact 24 so that these relays drop their contacts. The dropping of front contact 24 of relay SA deenergizes the stick circuit of relay S so that this relay is dropped before relay SAP connects (-1-) to this stick circuit at back contact 2|.

The dropping of iront Contact 29 of relay SAP deenergizes the stick circuits of the stepping relays which causes their release. The stepping relays at the repeater station are deenergized in a similar manner. Relay CK1 at the repeater station is deenergized by the dropping of iront contact |1I of relay SA1. The dropping of relay CK1 closes a circuit for positioning relay CS1 to the right before relay SAP drops, which circuit extends from (B+), back contact |13 of relay SAl, front contact |14 of relay SAP1, contact |15 of relay F2 in its neutral position, back contact |16 of relay L01, back contact |12 of relay 0K1 and winding of relay CS1, to (CN).

In the control office, the dropping of relay FP in response to the change to normal off" period closes a circuit for picking up relay LV which eX- tends from (1), front contact 29 of relay SAP, back contact 4|! of relay FP, back contact 4I of relay VP, front contact 44 of relay 3V and Winding of relay LV, to Relay LV closes an obvious stick circuit for itself at its front contact 50. Relay LV has no function in the control ofhce but the pick up circuit is shown to indicate hovv additional stepping relays are operated when provided and also to indicate how relay LV1 at the repeater station is picked up in response to the change to normal oil period. The picking up of relay LV1 opens the control line1 circuit at back contact 111 which deenergizes this line for dropping relays F2, F3, and FP2.

Since relay LV in the control ofce does not control the dropping of relays E and EP, the control line circuit is maintained open for a comparatively long interval of time. Since the picking up of relay LV1 at the repeater Station opens the control line1 circuit and maintains it open as long as relay LV1 is stuck up (which is until relay SAP1 is dropped), the control line1 circuit is maintained open for a comparatively long interval of time for dropping relays SA2 and SAP2 at the regular station. The dropping of relay SA2 deenergizes the stick circuit of relay CK3 at front Contact 262 before relay SAP2 energizes this stick circuit at back contact 263, thus resulting in dropping relay K3. The stepping relays at the regular station are released at the time relay SAP2 drops its contacts, because of the deenergization of their stick circuits in a similar manner as indicated in the control oice.

This places the system in its normal condition, from which it may be initiated in response to a new series of controls or a series of indications requiring transmission. It is believed that the above description of the detailed operation of the stepping relay bank in the control office and the general description of the stepping relay banks at the illustrated stations is suflicient to convey a complete understanding of the stepby-step and line impulsing operations of the system.

Stored ofice start conditions-lin the event that there are one or more storing relays picked up when the system advances into its normal condition, relay STR will be picked up to initiate another control cycle. More particularly, when relay SAP closes its back contact i8 any other SR relay which is picked up will close a front contact similar to i1 for again picking up relay STR. Before relay STR has time to pick up its contacts the deenergization of the stick circuits of the stepping relays at front contact 29 of relay SAP results in the dropping of these stepping relays. With all stepping relays down the circuit is again established through their back contacts I4, I5, and I for positioning relay CS to the right. Then when relay STR picks up its contacts relay S will be picked up and stuck up as previously explained for energizing the line circuit With a (-1-) impulse to initiate another cycle for the transmission of controls.

The picking up of front contact 28 of relay S closes an energizing circuit for relay SAP but before relay SAP has time to pick up its contacts this energizing circuit is opened at back contact 2S of relay FP. Therefore stored oice start conditions existing when no field start condition is stored, effects the picking up of relays SA and SAP in sequence in the order named. As will be later described, the existence of a stored start condition at a eld station when the system returns to its normal condition results in relays SAP and SA being picked up in sequence in the order named for marking the cycle as one for the transmission of indications.

Transmission of controls- It will be assumed that the system is initiated as above described and that step-by-step operation occurs in synchronism at the control cfiice and at the two stations illustrated, in the manner previously discussed. It will also be assumed that the repeater station responds to a code combination of (-1-) and that the regular station responds to a code combination of (-1-).

It has already been explained that the rst or conditioning impulse applied to the line circuit is (-1-) to mark the cycle as one for the transmission of controls. The second impulse is selected when relay IV picks up its contacts during the rst off period. In the assumed example, the picking up of relay IV closes a circuit for positioning relay CS to the right which extends from (B+), code jumper I, front contact 53 of relay CD, front contact i4 of relay IV, back contacts I5 and I6 of relays 2V and 3V respectively and Winding of relay CS, to (CN).

With relay CS positioned to the right during the first off period, the next impulse (first on) is (-1-) due to a circuit closed from the (-1-) terminal of battery B, Contact I in its right hand position, front contact of relay S, winding of relay F, back contact l2 of relay EP, control line conductor, Winding of relay F1, back contact |50 of relay CK2, return line conductor and contact I3 of relay CS in its right hand position to the terminal of lbattery B.

This impulse positions relay F1 to the right which closes a circuit for positioning relay CS1 to the right extending from (B+), contact |65 of relay F1 in its right hand. dotted position, front contact |66 of relay SA1,"front contact |12 of relay CKl and winding of relay CS1, to `(CN). Relay CS1 positioned to the right applies a impulse to control line1 over a circuit extending from the terminal of battery B1, contact `|52 of relay CS1 in its right hand position, front contact |54 of relay 0K1, winding of relay F2, back contacts |11, |55 and |56 of relays LV1, 3V1, and ZV1 respectively, front contact |51 of relay |V1, back contact |59 of relay CK2, back contact 6| of relay VP1, control linel, winding of relay F3, back contact 25|) of relay L02, back contact 356 of relay L03, return line1 and contact of relay CS1 in its right hand position to the terminal of battery BI.

This impulse repeated to control line1 positions relays F2 and F3 to the right. Relay F2 closes a circuit for positioning relay |PT1 to the right which extends from (B+), contact '|15 of relay F2 in its righthand Vdotted position, back contact |16 of relay L01, front contact-.|18 of relay CKl, front contact |19 Yof Vrelay FP1, back contacts |86 and |8| of relays 3V1 and ZV1 respectively, front contact |82 of relay |V1 and winding of relay |PT1, to (CN). Relay F3 closes a circuit for positioning relay |PT2 to the right which extends from (B+), contact 266 of relay F3 in its right hand dotted position, front contacts 26| and 265 of relays SA2 and FP2 respectively, back contact 266 of relay L02, backbontacts 261 and 268 of relays 3V2 and 2V2 respectively, vfront contact 269 of relay |V2 and Win'ding of relay |PT2, to (CN).

The `second station selecting impulse applied tothe control line is'selected when relay 2V is picked up during the second off period. This impulse is because relay CS is positioned to the left over a Acircuit extending from (B code jumper 52,Hfront contactV V5t of relay CD, front contact |5 ofrelayZV, back contact `|6 'of 4relay 3V and winding of relay CS, to' (CN).A 'Ihe actuation of contacts It and I3 of relay CS to their left handfdotted positions reverses the current flow overK thecontrol line circuitI from that previously described in connection 'with the first impulse, so that relays F and F1 are positioned to the left. Y Relay F1 closes a circuitfor positioning relay CS1 to the left extending from (B contact |65 of relay F1 in its left hand dotted position, `front contacts |66 and |12 of relays SA1 and 0K1 respectively and winding of relay CS1 to (CN). The positioning of contacts |5| and |52 of relay CS1 to their'left hand dotted positions reverses the current flow in vthe Ycontrol line1 so that relays'F2 and F3 are` positioned to the left.

Relay F2 closes a circuit for positioning relay 2PT1 to the left Which extends from (B contact |15 of relay F2 in its left hand dotted position, back contact |16 of relay L01, front contact |18 of relay CKl, front contact` |19 of relay FP1, back contact |80 of relay 3V1, front contact 8| fof relay 2V1`and Winding of relay 2PT1, to (CN). Relay F3 closes a circuit for positioning relay 2PT2 to the left extending from (B Contact v26|) of relay F3 in its left hand dotted position, front contacts 26| Vand 26.5 of relays SA2 and FP2 respectively, `back contact 266 of relay L02, back contact 261 of relay 3V2,

front contact 268 of relay 2V2 and winding of relay 2PT2, to (CN).

With relay |PT1 positioned tothe right and relay 2PT1` positioned to the left inresponse to the code as above described, the circuit for the third impulse is completed through the contacts of these two relays to the switch machine relay SMR1. Since relay |PT2 is positioned to the right and relay 2PT2 is positioned to the left, the circuit for switch machine relay SMR2 is not complete during the third impulse. It will be obvious that additional pilot relays can be provided for making up the circuits to the control relays at only a single station, which station responds to the station selecting code when the size of the system is increased, all in a manner similar vto the making up of these circuits inthe typical example just described.

InY the event that code jumper 5| is connected in its dotted line position to (B) and code jumper 52 Y,is connected in its dotted lineposition to (B+), then relay CS is positioned to the left on the rst station selecting step and to the right on thersecond station selecting step for providing a station selecting code of This positions relay F1 to the left on the first step and to the right on the second step for postioning relay CS1 to the left and right on the iirstandsecond steps respectively. This results in positioning relays F2 and F3 to the left andrighton the rst and second steps respectively, so that relays IPT1 and 2PT1 are positioned to the left and right respectively. Similarly relays |PT2 and 2PT2 are positioned to the left and to theright respectively. Relays |PT1 and 2PT1 in these positions do not complete circuits to the control relays, of which relay SMR1 is typical, but relays |PT2 and 2PT2 complete such control circuits.

4With the station* in Fig.` 3A selected, the third impulse is determined by the position of switch machine-lever SML in the control cnice, which in turn determines the position to which relay SMR1 will be actuated at the repeater station. For example, with lever SML in its right hand normal position a circuit is closed for positioning relay CS1 to the right which extends from (B+), contact 56 of lever SML in its right hand position, front contact 55 of relay CD, front contact I6 of relay 3V andwinding of relay CS, to (CN). This applies a impulse tothe contra] line for positioning relay F1 to the right which in turn positions relay CS1 to the right. This applied a impulse to control 1ine1 for positioning relays F2 and F3 to the right. Relay F3 is not eiective because the station illustrated in Fig. 4 has not been selected, but relay F2 closes a vcircuit for actuating relay SMR1 to the right which extends from (B+), contact |15 of relay F2 in its right hand dotted position, back contact |16 of relay L01, front contacts |18, |19 and |80 of relays 0K1, FP1, and 3V1 respectively, contact |83 of relay |PT1 in its right hand position, contact |84 of relay 2PT1 in its left hand dotted position and winding of relay SMR,1 to (CN). Relay SMR1 with its contact |85 positioned to the right closes a circuit for operating the switch machine for placing the track switch in its normal position.

In the event that lever SML is in its left hand dotted reverse position, then (B is connected through contact 56 in its left hand dotted posi- `tion and over the above described circuit for actuating relay CS to the left. This applies a impulse to the control line circuit which actuates relay F1 to the left. This actuates relay CS1 to the left for applying a impulse to the control line1 circuit for actuating relays F2 and F3 to the left. Contact |15 of relay F2 in its left hand dotted position closes a circuit from (B-) over the previously described path for operating relay SMR1 to the left, which in turn places the track switch in its reverse locked position.

In the event that the station illustrated in Fig. 4 is selected by a station selecting code of (-1-) impulses, then the third impulse determined by the switch machine lever in the control oiiice, which is associated with this station, is effective to position relay SMR2 to the right or left over a circuit which extends through contact 210 of relay |PT2 in its left hand dotted position and contact 21| of relay 2PT2 in its right hand position, in a manner which is similar to that described in connection with the operation of the corresponding relay at the repeater station.

The above examples indicate how two stations are selected, one having a station selecting code of (-1-) and the other a code of (-1) during two steps of the cycle. It will be obvious that four stations can be selected during these two steps of the cycle by making use of the two additional combinations (1-) (-1-) and In other words, code jumpers 5| and 52 in the control office can be connected in any one of their four possible combinations for selecting any one of four stations, each combination controlling the first two impulses of the cycle in accordance .with the particular combinations selected by the particular CD relay which is picked up at the beginning of the cycle. Similarly, these four stations are selectable by having the two pilot relays at each station positioned in all four of their possible positions for completing circuits which are effective on the following steps to control local control relays such as relays SMR1 and SMR2.

It will be understood that additional levers will be provided in the control oice associated with each station for controlling the signals at the selected station and signal control relays will be provided at each station for controlling these signals in accordance with the code combinations received from the control oice. This additional circuit arrangement has been omitted, since it is believed that the typical example illustrating the switch machine control is suflicient for an understanding of the complete operation.

Automatic start- When a change in condition occurs at a field station the change relay is dropped to initiate the system into a cycle of operations. If the change occursat the repeater station, relay CH1 is dropped for picking up relay L01 over a circuit extending from (-1-), back contact 202 of relay SAP1, back contact 203 of relay CK1, upper winding of relay L01 and back contact 204 of relay CH1, to Relay L01 closes a circuit for positioning relay CS1 to the left which extends from (B back contacts 205, 206, and 201 of relays Y|V1, 2V1,land 3V1 respectively, conductor 20|, front contact |16 of relay L01, back contact |12 of relay CK1 and winding of relay CS1, to (CN).

Relay CS1 in its left hand position closes a circuit for picking up relay CK2 which extends from (-1-), back contact |1| of relay SA1, contact |86 of relay CS1 in its left hand dotted position, back contact |81 of relay CK1 and lower winding of relay CK2, to Relay CK2 closes a stick circuit for itself extending from (-1-) back contact |68 of relay SAP1, back contact |69 of relay 0K1, front contact |88 and upper winding 0f relay CK2, t0 This stick circuit is maintained complete until the end of the cycle because relay SA1 closes its front contact |1| before relay SAP1 opens its back contact |68.

Relay CK2 closes its front contact |50 for energizing the control line with a impulse over a circuit extending from the (-1-) terminal of bat-- tery B1, contact |5| of relay CS1 in its left hand1 dotted position, front contact of relay CK2, winding of relay F1, control line conductor, back contact |2 of relay EP, winding of relay F, back contact of relay S, return line conductor and contact |52 of relay CS1 in its left hand dotted position to the terminal of battery B1. Current flowing over this circuit is effective to position relays F1 and F to the left. The operation of relays F1 and F close the previously described pick up circuits for relays FP1 and FP respectively, after which relays SA1, SAP1, SA and SAP are picked up as previously described.

Relay CK in the control oice is picked up over a circuit extending from (B contact 51 of relay F in its left hand dotted position, back contact 58 of relay SAP and upper winding of relay CK, to (B-1-). Relay CK closes a stick circuit for itself extending from (-1-), front contacts 59 and 60 in multiple of relays FP and SAy respectively, front contact 6| and lower winding of relay CK, to Since relay SA maintains its front contact 60 picked up until the end of the cycle relay CK remains stuck up throughout this cycle. The picking up of back contacts 20 and 22 of relay CK opens the pick up and stick circuits of relay S for a purpose which will be described in connection with stored oflice and indication start conditions. The picking up of back contact 62 of relay CK prevents the picking up of any CD relay.

Since this is the conditioning on period, the picking up of relays FP, SAP, FP1, and SAP1 cause relays VP and VP1 to be picked up as previously described. Since relay L01 is picked up, the opening of its back contact |53 disconnects the control line1 from the return line1, so that any other station farther out the line will be ineffective to energize the line circuit, when such a station has new indications to transmit during a cycle used for the transmission of indications by the repeater station. In other words, the picking up of back contact |53 of relay L01 locks out all inferior stations. A stick circuit is closed for relay L01, when relay SA1 picks up, which a extends from (-1-), front contact 208 of relay SA1, back contact 209 of relay 0K1, front contact 2|0 and lower winding of relay L01, to This stick circuit maintains relay L01 energized until the end of the cycle.

The picking up of relays SA, SAP, and VP in the control office cause relays E and EP to be picked up in the manner described in connection with the control cycle. Relay EP deenergizes the control line at back contact |2 to mark the beginning of the iirst off period. The step-bystep and impulsing operations continue in the same manner as described in connection with the transmission of controls, as far as impulsing the line is concerned. In this instance, however, the control line is energized by battery B1 at the repeater station instead of by battery B in the control oflice. This condition is clearly indicated in Fig. 1D showing relays F and F1 energized by battery B1 connected to the line circuit. This iigure also shows batteries B1 and B2 connected to the return line1 with the control line1 open. This open point is at back contact |53 of relay L01 as previously mentioned.

In the event that the regular station illustrated in Fig. 4 initiates the-system, the dropping of 'relayCH2 closes a circuitfor picking up relay L02 which extends from back contact 212 of relay SAP2, back contact 2'F3 of relay CK3, upper Winding of relay L02 and back contact 274 of relay CH2, to The picking up of back contact 2550i 'relayL02 renders the local control circuits ineffective and the picking up of contact 250 closes a circuit for energizing the control line1 with a impulse extending from the (-l-) terminal of battery B2, contact of relay CS2 in its left hand position, front contact 250 of relay L02, Winding of relay F3, co-ntrol line1, back contacts |53, |5'l, |56, |55 and lll of relays CK2, |V1, ZV1, 3V1, and LV1 respectively, winding of relay F2, back contacts |5 and |53 of relays CK1 and L01 respectively, return line1 and contact 252 of relay CS2 in its left hand position to the terminal of battery B2. Current in this circuit positions relays F3 and F2 to the left.

Relay F3 causes the picking up of relays FP2, SA2 and SAP2 in the previously described manner. The picking up of relay SA2 closes a stick circuit which maintains relay L02 energized throughout this cycle and which extends from (-1-), front contact 2lb of relay SA2, back con- -tact 275 of relay 0K3, front co-ntact 2TH and lower Winding of relay L02, to The picking up of back contact 25@ of relay'L02 locks out other stations farther out the line. v

This energization of control line1 marks the beginning of the cond-itioning on period by energizing line relays F2 and F3. Relay F2 closes the previously described circuit for positioning relay CS1 to the leit extending from (B at contact H5 in its left hand dotted position. Relay CK2 is picked up and stuck up as previously described in connection with the initiation of the system from the repeater station. The picking up of contact of relay CK2 energizes the control line circuit With current because relay CS1isin its left hand position. Relays F1 and F are energized as before, after which relays FP,

i CK, SA, and SAP in the control oiiice are picked up. Relays E and EP pick up to mark the end of the conditioning on period as previously described.

It Will thus be seen that the control line circuit extending from the repeater station to the ofce -is energized With a impulse When the system is initiated at the repeater station. A similar condition exists and in addition the control line1 circuit extending from the regular station to the repeater stat-ion is energized with a impulse when the system is initiated at the regular station. In the first instance the polarity of each impulse transmitted after the system is initiated at the repeater station, is determined by the station coole combination and the in-dications associated with the repeater station. When the system is initiated at the regular station, the impulses transmitted during succeeding steps of the cycle are determined in accordance With the code combination and the indications associated With the regular station.

Impulse repeating operation-It is believed desirable to give a brief summary o-f the impulse repeating operation during the transmission of controls, after which a brief outline of the impulse repeating operation during the transmission of indications Will begiven. It Will be recalled that during a control cycle, relay 0K1 at the repeater station is picked up and relay CK2 remains down. This is determined by the conditioning impulse applied to the control line being The end of the oir periods and the beginning of the on periods are marked off by the dropping of relay EP in the control ofilce, While the end of the onr periods and the beginning of the off lperiods are marked by the picking up of relay EP which energizes and deenergizcs respectively the control line.

In response to the energization of the control line at the beginning of the on periods, relay VP1 at the repeater station is shifted and in response to the deenergization of the control line at the beginning of the off periods, `a stepping relay is picked. up. The shifting of the VP relay in response to the energization of the control line repeats this condition by energizing the control line1 and the picking up of the stepping relay in response to the deenergization of the control line repeats this condition by deenergizing the control line1. Since relays F1 and FP1 must pick up and relay VP1 must shift during an on period before the control line1 is energized to start the on period in this line, the energization of the contro-l line1 lags behind the ener- Ygization of the control line by the time required to operate these three relays. Since relays F1 and FP1 must drop and the stepping relay must pick up in response to the deencrgization of the control line before the control line1 is deenergized, this deenergization of control line1 lags behind the deenergization of the control line by the time required for these three relays to opcrate.

During the transmission of indications, relay 0K1 at the repeater station is down and relay CK2 is picked up (as previously pointed out), irrespective of Whether the transmitting station is the repeater station or the regular station. This is due to tlierfact that the conditioning impulse applied to the control line is 0r course, when an indication cycle is initiated from the repeater station the control line1 is not iinpulsed because back contact |53 of relay L01 is picked up.

After the initiation of the system in the control oflce as above described, the control line is deenergized by the picking up of relay EP to mark the end of the on periods and the beginning of the 01T periods. The control line is energized by the dropping of relay EP to mark the end of the off periods and the beginning of the .on periods. Since relay E is controlled in its operation by the response of the stepping relay bank in the control oce, the control ofllce acts as the driver for the impulse operation during an indication cycle as Well as during a control cycle. i

onfperiods and the control line1 is energized in response to the picking up of a stepping relay during the off periods. This is just opposite to the operation during a control cycle, since during such a cycle the control line1 is energized in response to the shifting of relay VP1 and deenergized in response to the picking up of a stepping relay. This shift in the impulse operation during an indication cycle is brought about by the picking up of contacts |58, |59 and I6!) of relay CK2. In other Words, the control line1 connected to contact I6! of relay VP1 is transferred so that this line is energized through front contacts |6| and 594 of relays VP1 and CK2 respectively When thev odd stepping relays are picked up and energized through back contact |6| and front contact |60 when relay VP1 is down and the even stepping relays are picked up.

Therefore, the energization and deenergization of control line1 leads the energization and deenergization of the control line during an indication cycle, because the energization of the control line is in response to the operation of relay EP which responds to the operation of the stepping relay bank in the control oiice, while the energization and deenergization of the control line1 is in response to the operation of the stepping relay bank at the repeater station and since these stepping relay banks operate in synchronism, a lag is introduced between the response at the repeater station which energizes and deenergizes the control line1 and the response at the control oiiice which energizes and deenergizes the control line. This lag is that introduced by the dropping of relay EP. This transfer of the lagging operation makes it possible to condition the circuits during the ofi periods and to close up the executing circuits at the sending end in advance of theii1 closure at the receiving end when sending either way over the system, with impulse driving controlled in the oice in both cases.

Transmission of indications-It will rst be assumed that the repeater station initiates a cycle as above described for the transmission of indications. It will be assumed that the code combination of this station is provided on the rst two steps of the cycle as determined by the connection of jumpers 2| I and 2 I2 in Fig. 3B.

When stepping relay IV1 is picked up during the rst oir period a circuit is closed for positioning relay CS1 to the right which extends from (B+) jumper 2 I I, front contact 295 of relay |V1, back contacts 236 and 2Il'l of relays 2V1 and 3V1 respectively, conductor 29|, front contact |16 of relay L01, back contact |12 of relay CK1 and winding of relay CS1, to (CN). With relay CS1 positioned to the right the control line circuit is energized with a impulse during the next on period extending from the terminal of battery B1, contact |52 of relay CS1 in its righthand position, return line conductor, back contact l I of relay S, winding of relay F, back contact I2 of relay EP, control line, winding of relay F1, front contact |59 of relay CK2 and contact I5| of relay CS1 in its right-hand position to the terminal of battery B1.

With relay 2V1 picked up during the second oit period the above described circuit for relay CS1 extends through front contact 206 of relay 2V1 and jumper 2 I2 to (B-). This positions relay CS1 to the left so that tlre control line is energized during the next on period by a impulse, due to the reversal of the connection to the control line circuit from battery B1 at contacts II and |52.

With a impulse applied to the control line circuit at the rst step, relay F is positioned to the right which closes an indication receiving circuit ior positioning relay IPT to the right extending from (B+), contact 5'I of relay F in its right hand dotted position, front contact 58 of relay SAP, back contact 63 of relay S, back contact 64 of relay EP, back contacts 55 and 66 of relays 3V and 2V respectively, front contact 61 of relay IV and winding oi relay IPT, to (CN) The second impulse positions relay F to the left which closes the above described circuit from (B-) at the contact 5'I of relay F by way of iront contact 66 of relay 2V to position relay 2PT to the left. With relay IPT positioned to the right and with relay 2PT positioned to the left a circuit is closed for energizing station relay ST corresponding to the repeater station when relay 3V is picked up during the third 01T period. This circuit extends from front contact 68 of relay 3V, contact 'I0 of relay IPT in its right-hand position, contact 69 of relay 2PT in its left-hand position and winding of relay ST, to

The next impulse after the station registration code applied to the line circuit is or as determined by the position of track relay T1 of Fig. 3B. If the track is unoccupied relay T1 is picked up so that a circuit is closed from (B+) at front contact 2|3 of relay T1 and front contact 201 of relay 3V1 for positioning relay CS1 to the left. This applies a impulse to the control line circuit which positions relay F to the left. With contact 5l' of relay F in its left-hand dotted position, (B-) is connected by way of iront contact 65 of relay 3V and front contact 'II of relay -ST to the winding of relay IR, which positions relay IR to the left for deenergizing lamp OS as an indication that the track switch is unoccupied.

When the track switch is occupied, relay T1 drops to connect (B+) to relay CS1 for positioning this relay to the right which applies a impulse to the control line circuit for positioning relay F to the right. Contact 5'I of relay F in its right-hand dotted position connects (B+) by way of front contact 65 of relay 3V and front contact 'II or relay ST to relay IR for positioning this relay to the right. A circuit is now closed at contact T2 of relay IR in its right-hand dotto-tl position for lighting lamp OS as an indication that the track switch is occupied.

It will be obvious that other indications, such as the position of the track switch, the clear and stop signal indications and the like, may be transmitted on additional steps of the indication cycle in the same manner described for the transmission of the track occupancy indications just described. It is believed obvious that additional stations can be registered in the control oice by providing different code combinations in accordance with the connections of code jumpcrs such as 2|! and 2|2 of Fig. 3B at these additional stations. It is also believed obvious that in systems of larger size additional code jumpers can be selected on additional steps of the cycle to provide additional code combinations.

In the event that the regular station illustrated in Fig. 4 is transmitting indications during a cycle, the iirst impulse applied to the control line1 is as determined by relay CS2 being positioned to the left over a circuit extending from (B-), code jumper 218, front contact 253 of relay iV2, back contacts 254, 255, and 256 of relays 2V2, 3V2, and 0K3 respectively and winding of relay CS2, to (CN).

With relay CS2 positioned to the left a impulse is applied to the control line1 extending from the terminal oi battery B2, contact of relay CS2 in its left-hand position, front contact 25! of relay L02, winding of relay F3, control line1, front contact ISI of relay VP1, front contact |59 of relay CK2, front contact Il of relay IV1, back contacts |55, |55 and I'I'I of relays 2V1, 3V1, and LV1 respectively, winding of relay F2, back contacts |54 and |53 of relays 0K1 and L01 respectively, return line1 and contact 252 of relay CS2 in its left-hand position to the terminal of battery B2. This positions relays F3 and F2 to the left.

Relay F2 closes a circuit for positioning relay CS1 to the left which extends from (B+), contact |75 of relay F2 in its left-hand dotted position, back contacts |16 and |72 of relays L01 and CK1 respectively and winding of relay CS1, to (CN). With relay CS1 in its left-hand position a impulse is applied to the control line circuit through contacts I| and |52 as previously describe-d. This positions relay F to the left for connecting (B at Contact 5l of relay F in its left-hand dotted positionto relay lPT for positioning this relay to the left.

When relay 2V2 is picked up during the second oii period a circuit is closed for positioning relay CS2 to the right extending from (B+), code jumper 279, front contact 254 of relay 2V2 and over the remainder of the previously described circuit to relay CS2. With relay" CS2 Y positioned to the right a circuit is closed for energizing the control line1 circuit with a impulse which extends from the terminal of battery B2, contact 25| of relay CS2 in its righthand dotted position, return line1 conductor, back contacts |53 and |54 of relays L01 and CK1 respectively, winding of relay F2, back contacts lli and |55 of relays LV1 and 3V1 respectively, front Contact l of relay ZV1, front contact |50 of relay CK2, back contact Itl of relay VP1, control linel, winding of relay F3, front contact 255 of relay L02 and contact 252 of relay CS2 in its right-hand dotted position to the terminal of battery B2.

This impulse positions relay F2 to the right for closing the above-described circuit of relay CS1, which extends in this instance from (B+) at contact |25 of relay F2 in its right-hand dotted position. Relay CS1 is positioned to the right to app-ly a impulse from battery B1 to the control line circuit for positioning relay F to the right, which connects (B+) at contact 5l of relay F in its right-hand dotted position through front Contact t@ oi' relay 2V to the Winding of relay 2PT for positioning this relay to the right.

With relay lPT positioned to the left and relay ZZPT positioned to the right a circuit is closed from at front contact t8 of relay 3V, through contacts of relays IPT and ZPT (not shown) for energizing the station relay which corresponds to the station illustrated in Fig. 4.

The transmission of indications from the regular station takes place in a manner similar to that described in connection with its station registering code. This transmission is determined by track relay T2 positioning relay CS2 to the right or left in accordance with contact 28] of relay T2 in its dropped away or picked up condition respectively. Relay CS2 in its right or left-hand position, impulses the control line1 with a orV a impulse respectively for' positioning relay CS1, which repeats the received impulse over the control line for positioning relay F which in turn connects (B+) or (B at its contact 5l through front contact 65 of relay 3V and the front contact of the station relay corresponding to the regular station, to an indication receiving relay similar to relay IR. It is not believed necessary to describe this operation in detail since it is the same as similar typical opera-v tions above described.

The system is restored to its normal condition at the end of the cycle in the same manner as described in connection with a control cycle, when relay EP remains picked up for a sufficient time to cause relays SA and SAP to release. Since this produces a long deenergization of the control Relay .A CK2 is deenergized when re1aySA1=drops its front contact I'II which deenergizes the stick circuit of relay CK2 for an interval of time before this stick circuit is again energized by relay SAP1-dropping its back contact |68. Relay L01 is deenergized if the repeater station is transmitting by the dropping of front contact 2(38 of relay SA1. Relay L02 is deenergized if the regular station is transmitting when relay SA2 drops its iront contact 215.

The control Vlinelcircuit is deenergized to drop relays F3, FP2, SA2, and SAP2 when the regular station is transmitting, due to the picking up of back contact lll of relay LV1 at the repeater station-during the last off period in the control line circuit. Since relay LV1 is maintained picked up until relay SAP1 deenergizes its stick circuit, 'the control line1 circuit remains deenergized for a sufficient time to drop relays SA2 and SAP2. This interval of time may of course be increased slightly'to insure the dropping of relay SAP2 by making relay LV1 slow acting, so that the control line1 circuit is deenergized for an additional interval of time after that required to drop relay SAP1.

Stored oll'ice and field start conditions-1n the event that there are stored oflice and field start conditions existing at the end of a cycle the system functions to give preference to the field station. At the end of a control cycle, relay S is dropped when relay SA drops its front contact 22 and the stepping relays are dropped when relay SAP drops its front contact 29.

Since it is assumed that there is another SR relay picked up, due to a stored oflice start condition, a circuit is closed for picking up relay STR when relay SAP closes its back contact I8. This circuit extends from through a front contact of the picked up SR relay similar to iront contact Il. Relay CS will be positioned to the right when the stepping relays close their back contacts I4, I5, and I6.

When relay SA1 at the repeater station drops its front contact I1 I, relay CK1 is deenergized and when relay SAP1 drops its contacts the stepping relays at the repeater station are deenergized. Assuming that the repeater station has a stored start condition at this time, the dropping of back contact 202 of relay SAP1 closes a circuit for picking up relay L01 and relay CS1 is positioned to the left over the above-described circuit extending from (B at back contact 265 of relay IV1. Relay CK2 is picked up when relay CS1 closes its Contact |86 in its left-hand dotted position.

The picking up of relay STR in the control office closes the circuit for picking up relay S. With relay S picked up and with relay CK2 picked up the following battery connection is applied to the control line circuitz-From the terminal of battery B, contact Ill of relay CS in its righthand position, front contact II of relay S, Winding of relay F, back Contact I2 of relay EP, control line conductor, winding of relay F1, front contact |59 of relay CK2 and contact I5I of relay CS1 in its left-hand dotted position to the terminal of battery B1. From the terminal of battery B, contact I3 of relay CS in its righthand position, return line conductor and contact |52 of relay CS1 in its left-hand dotted position to the terminal of battery B1. Since like terminals of the control oioe and repeater station batteries are connected together in this circuit no current flow takes place Aover the control line. Therefore, relays F and'FP do not pick up.

Relay SAP Yis picked up over a circuit extending froml ,back contact 26 of relay FP, front contact 28 of relay S, back contact 21 of relay SA and winding of relay SAP, to The picking up of relay SAP deenergizes relay STR at back contact I8 and relay STR drops after a comparatively long interval of time. The picking up of relay SAP closes a circuit for picking up relay CK which extends from (-l) front contact similar to of the storing relay which is picked up, front contact I8 oi.' relay SAP, back contact 13 of relay SA, front contact 'I4 of relay STR and lower winding of relay CK, to This circuit is effective before relay STR has time to drop its contacts. The picking up of relay CK deenergizes relay S at back contacts 20 and 22 and the dropping of relay S disconnects the control office battery from the control line circuit and connects the control line and return line conductors together at back contact I I.

The control line is now energized from the repeater station battery which positions relays F and F1 to the left. Relays FP, FP1, SA, SA1, and SAP1 are now picked up over circuits previously described. The picking up of relay FP closes a stick circuit for relay CK extending from front contact 59 of relay FP, front contact 6| and lower winding of relay CK, to Relay SA connects at its front contact 60 to this stick circuit to maintain relay CK picked up throughout this cycle. The purpose of front contact 59 is so that contacts 60 and 13 of relay SA will not need to be of the make-before-break type.

Since relay S is down and relay CK is picked up in the control ofce and since relay CK2 is picked up and relay 0K1 is down at the repeater station, the cycle is marked for the transmission of indications which occur in the manner previously described. It will be apparent that the regular station causes the same operation under the above conditions because the control line circuit is energized from battery B1 in response to the initiation of the system from the regular station as well as from the repeater station.

Lock out-Referring to Figs. 3A, 3B, and 4, it will be assumed that the repeater station and the regular station have new indications ready to transmit at the same time with the system in its normal condition. The dropping of relay CH2 at the regular station picks up relay L02 over the previously described circuit. The picking up of relay L02 energizes the control line circuit1 with a impulse over the previously described circuit and relays F3, F2, FP2, and SA2 are picked up as previously described. Relay F2 positions its contacts to the left for positioning relay CS1 to the left, after which relay CK2 is picked up and stuck up by means of the previously described circuits.

The picking up of relay CK2 energizes the control line circuit with a impulse which positions relay F1 to the left, after which relays FP1, SA1, and SAP1 are picked up. The energization of the control line with a impulse positions relay F to the left for initiating the indication cycle, all as previously described.

The picking up of back contact 202 of relay SAP1 renders the pick-up circuit of lock-out relay L01 ineffective, so that the dropping of relay CH1 after the picking up of relay SAP1 prevents the repeater station obtaining access to the communication system. In other words, the picking up of relay SAPl, or similar relays at other superior stations, is the dead line beyond which no station can break in and take the communication system away from an inferior station.

In the event that relay CH1 drops its contact 204 for picking up relay L01 before this dead line is reached, then the control line1 is deenergized at back contact |53 so that an inferior station such as the regular station illustrated in Fig. 4 is dropped out, because the line circuit extending back from a superior station to an inferior station cannot be energized. This results in relays F3, FP2, SA2, SAP2, and L02 being dropped if they happen to be picked up at the time the superior station cuts in and takes possession of the communication system. In the event that all of the above-mentioned relays at the inferior station are not picked up at this time, those which are picked up will be dropped when the line circuit extending from a superior station to an inferior station is deenergized.

It will be understood that the system functions in the same manner when some station other than the station illustrated in Fig. 4 has new indications to transmit at the same time a station nearer the control oiiice has new indications ready for transmission. It will also be understood that the system functions as above irrespective of whether the stations involved are repeater stations or regular stations, since the lock-out relay such as relay L01 at a repeater station opens up the line circuit back towards inferior stations and the lock-out relay such as relay L02 opens up the line circuit from a regular station back towards other inferior stations.

Only at the station obtaining access to the communication system, are the indication circuits efiective. For example, when the repeater station maintains its lock-out relay L01 picked up, the indication conditioning circuit including conductor 20| is made effective at front contact |16 of relay L01. The indication conditioning circuit of an inferior station is rendered ineffective because the stepping relays do not operate to select the local indication circuits. At other stations between the station which obtains access to the line and the control oice, stepping takes place but at these stations the line cannot be interfered with because the associated lock-out relays are deenergized so that the continuity of the line circuit is maintained through these stations at back contacts similar to 250 of relay L02. In other Words, although stepping takes place and the code selecting relays at such stations are actuated the battery connection is not made to the line circuit at these stations because of open front contacts such as 250 of relay L02.

Having thus described one specic embodiment of a centralized tranic controlling system it is desired to be understood that the particular arrangements illustrated are merely typical of applicants invention and are not intended to show the exact circuit design necessary to carry out the features of the invention, but have been selected to facilitate in the disclosure rather than to limit its scope and it is further to be understood that various modifications may be made and various adaptations and alterations may be applied to the specific form disclosed in order to meet the various problems encountered in practice and that the system may be Varied in the number of repeater and regular stations, the amount of apparatus installed at the particular eld station and the number of steps provided for station selection and registration, all without in any manner departing from the spirit or scope of the invention except as limited by the appended claims.

What I claim is:-

1. In a remote control system, a control office, 

